In a Wireless Fidelity (Wi-Fi) phone in motion, a hand-over time is a very important factor in the quality of speech.
The Wi-Fi phone provides access to a new access point of another wireless Local Area Network (LAN) while in motion. At this time, the Wi-Fi phone goes through a series of processes for the access.
The access to the new access point must be provided quickly enough as not to be recognized by a phone user.
If the hand-over time is delayed, the phone user experiences mute or call disconnection.
The hand-over time is dependent on how security is set for the wireless LAN.
The security of the wireless LAN is based on Open (encryption-free) and various encryption standards such as Wired Equivalent Privacy (WEP), Wi-Fi Protected Access-Pre Shared Key (WPA-PSK), and Wi-Fi Protected Access (WPA). Among them, the WPA has the highest security level but the longest hand-over time.
An accessing process based on the WPA includes 802.1x authentication as illustrated in FIG. 1A, and generation of a data encryption key as illustrated in FIG. 1B.
Particularly, the 802.1x authentication takes much time because an authentication server (i.e., a Remote Authentication Dial-In User Service (RADIUS) server) interworks with the access point and terminals to transceive many messages, and thus has difficulty ensuring continuous hand-over.
Thus, studies are presently being made to reduce the hand-over time.
The representative study is Fast BSS Transition of IEEE802.11r.
However, the proposals of these studies are ongoing in an unstandardized state, and are considerably modified and complicated in comparison with an existing authentication scheme. As such, these schemes have a great difficult with easy application.
Further, in the light of to which access point the terminal provides access in the future, its range is not fixed, and thus it is difficult to easily handle a security aspect in order to ensure fast hand-over to any access point.